The German journal Psycho, 24 (1998), 726-731, discloses that reduced concentrations of Aβ1-42 are detectable in the CSF of patients with Alzheimer's disease. In these patients there is also a tendency for the concentration of N-terminally modified Aβ peptides Aβx-42 to be increased. By contrast, there are said to be no changes in concentration of the Aβ peptide Aβ1-40 because of Alzheimer's disease. The concentrations of the Aβ peptides Aβ1-42 and Aβ1-40 in the CSF of Alzheimer patients are said to show no absolute correlation with clinical or psychological test parameters of the severity of the dementia, although there is said to be great intraindividual constancy thereof.
There is known to be evidence that sAPPα is also reduced in the CSF in Alzheimer dementia.
In order to obtain more detailed information about the correlation of dementing disorders and possibly other neuropsychatric disorders with the concentration of all or certain of the Aβ peptides in samples of body fluids or tissues it is necessary to have means available for very accurate and reproducible determination of the concentrations of the Aβ peptides, so that existing correlations are not obscured by unavoidable errors in the concentration determinations.